Drone operators fly an MQ-9 Reaper training mission from a ground control station at Holloman Air Force Base, New Mexico, in this US Air Force handout photo taken October 3, 2012. Photo: Reuters

A Draganflyer X6, six-rotor remote controlled helicopter which can fly up to 20 mph and travel up to a quarter mile away and 400 feet high, is pictured at the Grand Valley Model Airfield in Mesa County, Colorado on January 31, 2013. The Draganflyer X6 is a property of Mesa County Sheriff's Department. As the US prepares for the introduction of thousands of unarmed drones into its airspace in 2015, police, first responders and experts already flying domestic drones have begun to confront some of the privacy, regulatory and safety concerns that are beginning to surface. Photo: Reuters

A German Bundeswehr armed forces Heron 1 unmanned aerial vehicle (UAV) takes off for a mission from the Marmal army camp in Mazar-e-Sharif, northern Afghanistan December 11, 2012. German air forces are using the reconnaissance drone aircraft for the ongoing International Security Assistance Force (ISAF) mission. Photo: Reuters

A US Air Force MQ-1 Predator unmanned aerial vehicle assigned to the California Air National Guard's 163rd Reconnaissance Wing flies near the Southern California Logistics Airport in Victorville, California in this January 7, 2012. Photo: Reuters

A US Marine with Marine Unmanned Aerial Vehicle Squadron 1 pushes an RQ-7B Shadow UAV following its landing at Camp Leatherneck, Afghanistan in this November 10, 2011. Photo: Reuters

Civil contractors make the final technical checks on a German Bundeswehr armed forces Heron 1 unmanned aerial vehicle (UAV) before it takes off for a mission at the Marmal army camp in Mazar-e-Sharif, northern Afghanistan December 11, 2012. German air forces are using the reconnaissance drone aircraft for the ongoing International Security Assistance Force (ISAF) mission. Photo: Reuters

Personnel at a Navy testing facility in Dahlgren, Virginia, launch an Insitu ScanEagle unmanned aerial vehicle during a demonstration for leaders from the Coast Guard Acquisition Directorate in this May 3, 2012 handout photo obtained by Reuters December 5, 2012. Photo: Reuters

A ScanEagle Unmanned Aerial Vehicle is pictured on display at the Naval Air Station Patuxent River in St. Inigoes, Maryland in this June 27, 2005 handout photo obtained by Reuters December 5, 2012. According to the US Navy, the ScanEagle is an affordable, runway-independent, long-endurance, autonomous, unmanned vehicle designed to provide persistent intelligence, surveillance and reconnaissance date, and battlefield damage assessment and/or communications relay. Photo: Reuters

The United States Air Force's Global Hawk unmanned spy plane at the Royal Australian Air Force Base, Edinburgh near Adelaide, sits on the tarmac after making a non-stop flight across the Pacific April 24, 2001. The unmanned high altitude jet-powered aircraft made aviation history by completing the first non-stop, robotic flight across the Pacific to Australia from Edwards Air Force Base in California to Edinburgh in Adelaide. Photo: Reuters

A MAV US military surveillance drone camera flies in Musa Qal-Ah district in Helmand province, southwestern Afghanistan October 31, 2012. Photo: Reuters

Reuters and other foreign media are subject to Iranian restrictions on leaving the office to report, film or take pictures in Tehran. An undated picture received December 8, 2011 shows a member of Iran's revolutionary guard pointing at the US RQ-170 unmanned spy plane as he speaks with Amirali Hajizadeh (R), a revolutionary guard commander, at an unknown location in Iran. The unmanned US drone Iran said it had captured was programmed to automatically return to base even if its data link was lost, one key reason that US officials say the drone likely malfunctioned and was not downed by Iranian electronic warfare. Photo: Reuters

A photographer takes pictures of an Israel Aero Space Industries (IAI) Heron 1 unmanned aerial vehicle (UAV) during a media presentation at the airbase in the central Swiss town of Emmen September 20, 2012. Photo: Reuters

An Israel Aero Space Industries (IAI) Heron 1 unmanned aerial vehicle (UAV) approaches to land, during a media presentation at the airbase in the central Swiss town of Emmen September 20, 2012. Photo: Reuters

A man films a BAE Systems potential concept model of an unmanned combat system, also known as a drone, at the Farnborough Airshow 2012 in southern England July 11, 2012. Photo: Reuters

The RQ-4A Global Hawk, a high-altitude, long-endurance unmanned aerial reconnaissance system designed to provide military field commanders with high resolution, near-real-time imagery of large geographic areas is pictured at a hanger at a forward deployed location waiting to fly its next mission supporting Operation Enduring Freedom. Photo: Reuters

An unarmed US "Shadow" drone. A US offer to supply Pakistan with its own fleet of surveillance drone aircraft delighted Islamabad but now threatens to turn into another source of friction between the two nations. Photo: Reuters

An unarmed US "Shadow" drone is launched in this undated photograph. Photo: Reuters

A German ISAF soldier of the Quick Reaction Force regional command north (QRF) launched an Aladin mini drone UAV during a drill in the Marmal mountains near the German ISAF headquarters in Masar-i-Sharif, north of Kabul. Photo: Reuters

A computer controlled US Air Force drone during a test flight in the Micro Air Vehicle lab at Wright Patterson Air Force Base in Dayton, Ohio. The Micro Air Vehicles unit of the Air Force Research Laboratory at Wright Patterson AFB is developing small military drones, with the goal of making them so small that they resemble small birds and insects, including some that will have moving wings. The mission is to develop MAVs that can find, track and target adversaries while operating in complex urban environments. The engineers are using a variety of small helicopters and drones in the lab to develop the programs and software. Testing takes place in a controlled indoor lab where the team flies the MAVs and then gathers data to analyse for further development. Photo: Reuters

An employee displays the assembly of an unmanned aerial vehicle (UAV) at the Integrated Dynamics research and development centre in Karachi. In Pakistan's commercial hub, a Pakistani is developing his own drone technology despite security challenges arising from the current political climate and the public anger over the US use of the unmanned aircrafts. Located in a narrow industrial lane in Karachi is the 90,000 square-foot research facility called Integrated Dynamics. There, Raja Sabri Khan, the company's chief executive, makes UAVs, commonly known as drones. But his are for civilian and scientific research. Photo: Reuters

A Heron TP, also known as the IAI Eitan, surveillance unmanned air vehicle (UAV) flies during an official inauguration ceremony at Tel Nof Air Force Base near Tel Aviv. An Israeli air force officer said the Israeli-made drone is larger than any other drone and can fly at higher altitudes, while carrying more weight including advanced technological systems. The officer said the drone's main advantage was its longer flying time, estimated at 20 hours. Photo: Reuters

An Israeli-made Heron unmanned drone aircraft is seen during a presentation to journalists. Photo: Reuters

The internal avionics section of a General Atomics MQ-9 Predator B drone is seen in the predator's hanger at Fort Huachuca, Arizona. The remote piloted drone has a maximum altitude of 50,000 feet and is used to detect undocumented immigrants entering the United States illegally from Mexico. Photo: Reuters

Israeli military personnel prepare a drone for a mission at Palmachim air force base near Rishon Lezion. Photo: Reuters

Israeli soldiers fly the new drone (remote-piloted vehicle). The new drone is part of the "SkyLite" family of mini remote-piloted vehicles that gather intelligence for field and special forces using an electro optic sensor. Photo: Reuters

German soldiers stand behind an unmanned Luna military reconnaissance drone during a media presentation. Photo: Reuters